The influence of nasal abnormalities in adherence to continuous positive airway pressure device therapy in obstructive sleep apnea patients.

BACKGROUND: The few studies that examine the effect of nasal abnormalities on continuous positive airway pressure device (CPAP) adherence are controversial. The aim of this study was to evaluate the contribution of nasal abnormalities in CPAP adherence. METHODS: We included patients with moderate to severe OSA. The patients were submitted to rhinoscopy, nasofibroscopy, nasal inspiratory peak flow, and acoustic rhinometry. The patients who used a CPAP for 4 h or more per night for at least 70 % of the nights over a 6-month period were considered to have good adherence. RESULTS: Thirty-four patients finished the study. Eleven (33.4 %) were female and 23 (67.6 %) were male. Sixteen (47.1 %) patients had good adherence. The body mass index (p = 0.030), neck circumference (p = 0.006), and apnea-hypopnea index (p = 0.032) were higher, and the oxyhemoglobin saturation minimum was lower (p = 0.041) in the good adherence group. Nasal parameters showed no differences between good and poor adherence groups. In Spearman's correlation, surprisingly, there was a negative correlation between the highest number of hours of CPAP use with smaller values of nasal minimal cross-sectional areas in the supine position (r, 0.375; p = 0.029). In the linear regression model, the nasal findings that predicted increased of the CPAP use were the following: lower scores of nasal symptoms (p = 0.007) and lower nasal volume in supine position (p = 0.001). CONCLUSIONS: The majority of the nasal parameters evaluated in this study did not influence CPAP adherence.

Atrial Fibrillation (Part 1): Pathophysiology, Risk Factors, and Therapeutic Basis. / Fibrilação Atrial (Parte 1): Fisiopatologia, Fatores de Risco e Bases Terapêuticas.

Atrial fibrillation is the most common sustained arrhythmia in clinical practice, with a preference for older age groups. Considering population ageing, the projections for the next decades are alarming. In addition to its epidemiological importance, atrial fibrillation is evidenced by its clinical repercussions, including thromboembolic phenomena, hospitalizations, and a higher mortality rate. Its pathophysiological mechanism is complex and involves an association of hemodynamic, structural, electrophysiological, and autonomic factors. Since the 1990s, the Framingham study of multivariate analyses has demonstrated that hypertension, diabetes, heart failure, and valvular disease are independent predictors of this rhythm abnormality along with age. However, various other risk factors have been recently implicated in an increase of atrial fibrillation cases, such as sedentary behavior, obesity, sleep disorders, tobacco use, and excessive alcohol use. Moreover, changes in quality of life indicate a reduction in atrial fibrillation recurrence, thus representing a new strategy for excellence in the treatment of this cardiac arrhythmia. Therapeutic management involves a broad knowledge of the patient's health state and habits, comprehending 4 main pillars: lifestyle changes and rigorous treatment of risk factors; prevention of thromboembolic events; rate control; and rhythm control. Due to the dimension of factors involved in the care of patients with atrial fibrillation, integrated actions performed by interprofessional teams are associated with the best clinical results.

A fibrilação atrial é a arritmia sustentada mais comum na prática clínica com predileção pelas faixas etárias mais avançadas. Com o envelhecimento populacional, as projeções para as próximas décadas são alarmantes. Além de sua importância epidemiológica, a fibrilação atrial é destacada por suas repercussões clínicas, incluindo fenômenos tromboembólicos, hospitalizações e maior taxa de mortalidade. Seu mecanismo fisiopatológico é complexo, envolvendo uma associação de fatores hemodinâmicos, estruturais, eletrofisiológicos e autonômicos. Desde os anos 1990, o estudo Framingham em análises multivariadas já demonstrou que, além da idade, a presença de hipertensão, diabetes, insuficiência cardíaca e doença valvar é preditor independente dessa normalidade do ritmo. Entretanto, recentemente, vários outros fatores de risco estão sendo implicados no aumento do número de casos de fibrilação atrial, tais como sedentarismo, obesidade, anormalidades do sono, tabagismo e uso excessivo de álcool. Além disso, as mudanças na qualidade de vida apontam para uma redução na recorrência de fibrilação atrial, tornando-se uma nova estratégia para o tratamento de excelência dessa arritmia cardíaca. A abordagem terapêutica envolve um amplo conhecimento do estado de saúde e hábitos do paciente, e compreende quatro pilares principais: mudança de hábitos de vida e tratamento rigoroso de fatores de risco; prevenção de eventos tromboembólicos; controle da frequência; e controle do ritmo. Pela dimensão de fatores envolvidos no cuidado ao paciente portador de fibrilação atrial, ações integradas com equipes multiprofissionais estão associadas aos melhores resultados clínicos.

Recommendations for the Post-Mortem Management of Cardiac Implantable Electronic Devices. / Recomendações para o Manejo de Dispositivos Cardíacos Eletrônicos Implantáveis Post Mortem.

The management of cardiac implantable electronic devices after death has become a source of controversy. There are no uniform recommendations for such management in Brazil; practices rely exclusively on institutional protocols and regional custom. When the cadaver is sent for cremation, it is recommended to remove the device due to the risk of explosion and damage to crematorium equipment, in addition to other precautions. Especially in the context of the SARS-CoV-2 pandemic, proper guidance and organization of hospital mortuary facilities and funeral services is essential to minimize the flow of people in contact with bodily fluids from individuals who have died with COVID-19. In this context, the Brazilian Society of Cardiac Arrhythmias has prepared this document with practical guidelines, based on international publications and a recommendation issued by the Brazilian Federal Medical Council.

O manejo de dispositivos cardíacos eletrônicos implantáveis de pacientes que evoluem a óbito tem sido motivo de controvérsia. Em nosso meio, não há recomendações uniformes, estando baseadas exclusivamente em protocolos institucionais e em costumes regionais. Quando o cadáver é submetido para cremação, além de outros cuidados, recomenda-se a retirada do dispositivo devido ao risco de explosão e dano do equipamento crematório. Principalmente no contexto da pandemia causada pelo SARS-Cov-2, a orientação e organização de unidades hospitalares e serviços funerários é imprescindível para minimizar o fluxo de pessoas em contato com fluidos corporais de indivíduos falecidos por COVID-19. Nesse sentido, a Sociedade Brasileira de Arritmias Cardíacas elaborou este documento com orientações práticas, tendo como base publicações internacionais e recomendação emitida pelo Conselho Federal de Medicina do Brasil.

Development and clinical validation of a non-invasive, beat-to-beat blood pressure monitoring device, compared to invasive blood pressure monitoring during coronary angiography.

OBJECTIVE: To develop and test a beat-to-beat blood pressure monitoring device during coronary angiography, and compare it with invasive blood pressure monitoring. METHODS: Twenty-eight patients with an indication for hemodynamic study were selected for this investigation, and kept in supine position. Before starting the coronary angiography, they were instructed about the use of the left radial bracelet for beat-to-beat blood pressure monitoring. RESULTS: There was a significant difference between the time required for the catheterization laboratory team to acquire the first invasive blood pressure reading and the time to obtain the first beat-to-beat reading (11.1±5.1 and 1.5±1.8, respectively; p<0.0001). The intraclass correlation coefficients (95%CI) of systolic and diastolic blood pressures were 0.897 (0.780-0.952) and 0.876 (0.734-0.942), indicating good reproducibility. CONCLUSION: This study showed the process to develop a beat-to-beat blood pressure monitoring device. When compared to invasive blood pressure monitoring, there were no significant differences between the two methods. This technique may play a promising coadjuvant role when combined with invasive monitoring during coronary angiography procedures.

Effects of Exercise Training and CPAP in Patients With Heart Failure and OSA: A Preliminary Study.

BACKGROUND: Exercise and CPAP improve OSA. This study examined the effects of exercise in patients with heart failure (HF) and OSA. METHODS: Patients with HF and OSA were randomized to the following study groups: control, exercise, CPAP, and exercise + CPAP. RESULTS: Sixty-five participants completed the protocol. Comparing baseline vs 3 months, the mean apnea-hypopnea index (AHI) did not change significantly (in events per hour) in the control group, decreased moderately in the exercise group (28 ± 17 to 18 ± 12; P < .03), and decreased significantly more in the CPAP group (32 ± 25 to 8 ± 11; P < .007) and in the exercise + CPAP group (25 ± 15 to 10 ± 16; P < .007). Peak oxygen consumption, muscle strength, and endurance improved only with exercise. Both exercise and CPAP improved subjective excessive daytime sleepiness, quality of life, and the New York Heart Association functional class. However, compared with the control group, changes in scores on the 36-item Medical Outcomes Study Short Form Survey and Minnesota Living with Heart Failure Questionnaire were only significant in the exercise groups. CONCLUSIONS: In patients with HF and OSA, our preliminary results showed that exercise alone attenuated OSA and improved quality of life more than CPAP. In the landscape treatment of OSA in patients with HF, this analysis is the only randomized trial showing any treatment (in this case, exercise) that improved all the studied parameters. The results highlight the important therapeutic benefits of exercise, particularly because adherence to CPAP is low.

Fibrilação Atrial (Parte 1): Fisiopatologia, Fatores de Risco e Bases Terapêuticas / Atrial Fibrillation (Part 1): Pathophysiology, Risk Factors, and Therapeutic Basis

Resumo A fibrilação atrial é a arritmia sustentada mais comum na prática clínica com predileção pelas faixas etárias mais avançadas. Com o envelhecimento populacional, as projeções para as próximas décadas são alarmantes. Além de sua importância epidemiológica, a fibrilação atrial é destacada por suas repercussões clínicas, incluindo fenômenos tromboembólicos, hospitalizações e maior taxa de mortalidade. Seu mecanismo fisiopatológico é complexo, envolvendo uma associação de fatores hemodinâmicos, estruturais, eletrofisiológicos e autonômicos. Desde os anos 1990, o estudo Framingham em análises multivariadas já demonstrou que, além da idade, a presença de hipertensão, diabetes, insuficiência cardíaca e doença valvar é preditor independente dessa normalidade do ritmo. Entretanto, recentemente, vários outros fatores de risco estão sendo implicados no aumento do número de casos de fibrilação atrial, tais como sedentarismo, obesidade, anormalidades do sono, tabagismo e uso excessivo de álcool. Além disso, as mudanças na qualidade de vida apontam para uma redução na recorrência de fibrilação atrial, tornando-se uma nova estratégia para o tratamento de excelência dessa arritmia cardíaca. A abordagem terapêutica envolve um amplo conhecimento do estado de saúde e hábitos do paciente, e compreende quatro pilares principais: mudança de hábitos de vida e tratamento rigoroso de fatores de risco; prevenção de eventos tromboembólicos; controle da frequência; e controle do ritmo. Pela dimensão de fatores envolvidos no cuidado ao paciente portador de fibrilação atrial, ações integradas com equipes multiprofissionais estão associadas aos melhores resultados clínicos.

Abstract Atrial fibrillation is the most common sustained arrhythmia in clinical practice, with a preference for older age groups. Considering population ageing, the projections for the next decades are alarming. In addition to its epidemiological importance, atrial fibrillation is evidenced by its clinical repercussions, including thromboembolic phenomena, hospitalizations, and a higher mortality rate. Its pathophysiological mechanism is complex and involves an association of hemodynamic, structural, electrophysiological, and autonomic factors. Since the 1990s, the Framingham study of multivariate analyses has demonstrated that hypertension, diabetes, heart failure, and valvular disease are independent predictors of this rhythm abnormality along with age. However, various other risk factors have been recently implicated in an increase of atrial fibrillation cases, such as sedentary behavior, obesity, sleep disorders, tobacco use, and excessive alcohol use. Moreover, changes in quality of life indicate a reduction in atrial fibrillation recurrence, thus representing a new strategy for excellence in the treatment of this cardiac arrhythmia. Therapeutic management involves a broad knowledge of the patient's health state and habits, comprehending 4 main pillars: lifestyle changes and rigorous treatment of risk factors; prevention of thromboembolic events; rate control; and rhythm control. Due to the dimension of factors involved in the care of patients with atrial fibrillation, integrated actions performed by interprofessional teams are associated with the best clinical results.

Recomendações para o manejo de dispositivos cardíacos eletrônicos implantáveis post mortem / Recommendations for the post-mortem management of cardiac implantable electronic devices

O manejo de dispositivos cardíacos eletrônicos implantáveis de pacientes que evoluem a óbito tem sido motivo de controvérsia. Em nosso meio, não há recomendações uniformes, estando baseadas exclusivamente em protocolos institucionais e em costumes regionais. Quando o cadáver é submetido para cremação, além de outros cuidados, recomenda-se a retirada do dispositivo devido ao risco de explosão e dano do equipamento crematório. Principalmente no contexto da pandemia causada pelo SARS-Cov-2, a orientação e organização de unidades hospitalares e serviços funerários é imprescindível para minimizar o fluxo de pessoas em contato com fluidos corporais de indivíduos falecidos por COVID-19. Nesse sentido, a Sociedade Brasileira de Arritmias Cardíacas elaborou este documento com orientações práticas, tendo como base publicações internacionais e recomendação emitida pelo Conselho Federal de Medicina do Brasil.

The management of cardiac implantable electronic devices after death has become a source of controversy. There are no uniform recommendations for such management in Brazil; practices rely exclusively on institutional protocols and regional custom. When the cadaver is sent for cremation, it is recommended to remove the device due to the risk of explosion and damage to crematorium equipment, in addition to other precautions. Especially in the context of the SARS-CoV-2 pandemic, proper guidance and organization of hospital mortuary facilities and funeral services is essential to minimize the flow of people in contact with bodily fluids from individuals who have died with COVID-19. In this context, the Brazilian Society of Cardiac Arrhythmias has prepared this document with practical guidelines, based on international publications and a recommendation issued by the Brazilian Federal Medical Council.

Sleep Apnea and Nocturnal Cardiac Arrhythmia: A Populational Study.

Background: The mechanisms associated with the cardiovascular consequences of obstructive sleep apnea include abrupt changes in autonomic tone, which can trigger cardiac arrhythmias. The authors hypothesized that nocturnal cardiac arrhythmia occurs more frequently in patients with obstructive sleep apnea. Objective: To analyze the relationship between obstructive sleep apnea and abnormal heart rhythm during sleep in a population sample. Methods: Cross-sectional study with 1,101 volunteers, who form a representative sample of the city of São Paulo. The overnight polysomnography was performed using an EMBLA® S7000 digital system during the regular sleep schedule of the individual. The electrocardiogram channel was extracted, duplicated, and then analyzed using a Holter (Cardio Smart®) system. Results: A total of 767 participants (461 men) with a mean age of 42.00 ± 0.53 years, were included in the analysis. At least one type of nocturnal cardiac rhythm disturbance (atrial/ventricular arrhythmia or beat) was observed in 62.7% of the sample. The occurrence of nocturnal cardiac arrhythmias was more frequent with increased disease severity. Rhythm disturbance was observed in 53.3% of the sample without breathing sleep disorders, whereas 92.3% of patients with severe obstructive sleep apnea showed cardiac arrhythmia. Isolated atrial and ventricular ectopy was more frequent in patients with moderate/severe obstructive sleep apnea when compared to controls (p < 0.001). After controlling for potential confounding factors, age, sex and apnea-hypopnea index were associated with nocturnal cardiac arrhythmia. Conclusion: Nocturnal cardiac arrhythmia occurs more frequently in patients with obstructive sleep apnea and the prevalence increases with disease severity. Age, sex, and the Apnea-hypopnea index were predictors of arrhythmia in this sample.

Development and clinical validation of a non-invasive, beat-to-beat blood pressure monitoring device, compared to invasive blood pressure monitoring during coronary angiography / Desenvolvimento e validação clínica de equipamento para medida de pressão arterial não invasiva, batimento a batimento, comparado ao de pressão arterial invasiva durante procedimentos de angiocoronariografia

ABSTRACT Objective To develop and test a beat-to-beat blood pressure monitoring device during coronary angiography, and compare it with invasive blood pressure monitoring. Methods Twenty-eight patients with an indication for hemodynamic study were selected for this investigation, and kept in supine position. Before starting the coronary angiography, they were instructed about the use of the left radial bracelet for beat-to-beat blood pressure monitoring. Results There was a significant difference between the time required for the catheterization laboratory team to acquire the first invasive blood pressure reading and the time to obtain the first beat-to-beat reading (11.1±5.1 and 1.5±1.8, respectively; p<0.0001). The intraclass correlation coefficients (95%CI) of systolic and diastolic blood pressures were 0.897 (0.780-0.952) and 0.876 (0.734-0.942), indicating good reproducibility. Conclusion This study showed the process to develop a beat-to-beat blood pressure monitoring device. When compared to invasive blood pressure monitoring, there were no significant differences between the two methods. This technique may play a promising coadjuvant role when combined with invasive monitoring during coronary angiography procedures.

RESUMO Objetivo Desenvolver e validar um equipamento para monitorização de pressão arterial batimento a batimento, durante a realização de coronariografia, e comparar com as medidas de pressão arterial invasiva obtidas. Métodos Foram selecionados 28 pacientes com indicação de estudo hemodinâmico, que permaneceram em decúbito dorsal horizontal e, antes do início da coronariografia, foram orientados quanto ao uso da pulseira radial esquerda para monitorização da pressão arterial batimento a batimento. Resultados Houve diferença significativa entre o tempo necessário para a equipe de hemodinâmica adquirir a primeira medida da pressão arterial invasiva e o tempo da primeira medida da pressão arterial batimento a batimento (11,1±5,1 e 1,5±1,8, respectivamente; p<0,0001). Os coeficientes de correlação intraclasse (IC95%) da pressão arterial sistólica e da diastólica foram 0,897 (0,780-0,952) e 0,876 (0,734-0,942), indicando boa reprodutibilidade. Conclusão Este estudo demonstrou o processo de desenvolvimento de um equipamento para avaliação da pressão arterial batimento a batimento. Quando comparado com a pressão arterial invasiva, não foram encontradas diferenças significativas entre as duas medidas. Essa técnica pode constituir ferramenta coadjuvante promissora, associada à monitorização invasiva, durante procedimentos de coronariografia.

The use of external event monitoring (web-loop) in the elucidation of symptoms associated with arrhythmias in a general population.

OBJECTIVE: To correlate arrhythmic symptoms with the presence of significant arrhythmias through the external event monitoring (web-loop). METHODS: Between January and December 2011, the web-loop was connected to 112 patients (46% of them were women, mean age 52±21 years old). Specific arrhythmic symptoms were defined as palpitations, pre-syncope and syncope observed during the monitoring. Supraventricular tachycardia, atrial flutter or fibrillation, ventricular tachycardia, pauses greater than 2 seconds or advanced atrioventricular block were classified as significant arrhythmia. The association between symptoms and significant arrhythmias were analyzed. RESULTS: The web-loop recorded arrhythmic symptoms in 74 (66%) patients. Of these, in only 14 (19%) patients the association between symptoms and significant cardiac arrhythmia was detected. Moreover, significant arrhythmia was found in 11 (9.8%) asymptomatic patients. There was no association between presence of major symptoms and significant cardiac arrhythmia (OR=0.57, CI95%: 0.21-1.57; p=0.23). CONCLUSION: We found no association between major symptoms and significant cardiac arrhythmia in patients submitted to event recorder monitoring. Event loop recorder was useful to elucidate cases of palpitations and syncope in symptomatic patients.

Executive functioning in obstructive sleep apnea syndrome patients without comorbidities: focus on the fractionation of executive functions.

PURPOSE: Obstructive sleep apnea syndrome (OSAS) is associated with impaired cognition, especially executive functions. However, various of its comorbid conditions are also known to cause cognitive impairment, so it is unclear whether OSAS itself is responsible for cognitive deficits. Our aim was to determine the effects of OSAS on executive functions in otherwise healthy patients. METHOD: This was a parallel group design study, which involved 22 patients aged 36-65 years diagnosed with moderate to severe OSAS, whose body mass index was below 26, and who did not have diabetes, hypertension, or depression. Controls were 22 healthy individuals with similar age, gender, intelligence quotient, and schooling to those of the patients. Participants completed a test battery that included measures of 6 distinct executive domains (shifting, inhibition, updating, dual-task performance, planning, and access to long-term memory), of all subsystems of the multiple-component working memory model, attention, and mood. RESULTS: OSAS and controls were equivalent in all demographic variables and test scores. The apnea-hypopnea index did not significantly correlate with executive performance, but mean oxygen saturation did so with measurements of executive shifting and access to long-term memory. CONCLUSIONS: OSAS without comorbidities did not lead to cognitive impairment.

Recommendations of the Brazilian Society of Cardiac Arrhythmias for holter monitoring services.

BACKGROUND: There are innumerous indicators to assure the quality of a service. However, medical competence and the proper performance of a procedure determine its final quality. The Brazilian Society of Cardiac Arrhythmias recommends minimum parameters necessary to guarantee the excellence of ambulatory electrocardiographic monitoring services. OBJECTIVE: To recommend minimum medical competences and the information required to issue a Holter monitoring report. METHODS: This study was grounded in the concept of evidence-based medicine and, when evidence was not available, the opinion of a writing committee was used to formulate the recommendation. That committee consisted of professionals with experience on the difficulties of the method and management in providing services in that area. RESULTS: The professional responsible for the Holter monitoring analysis should know cardiovascular pathologies and have consistent formation on electrocardiography, including cardiac arrhythmias and their differential diagnoses. The report should be written in a clear and objective way. The minimum parameters that comprise a Holter report should include statistics of the exam, as well as quantification and analysis of the rhythm disorders observed during monitoring. CONCLUSION: Ambulatory electrocardiographic monitoring should be performed by professionals knowledgeable about electrocardiographic analysis, whose report should comprise the minimum parameters mentioned in this document.

Cardiovascular profile in patients with obstructive sleep apnea.

BACKGROUND: Obstructive Sleep Apnea (OSA) is a risk factor for several cardiovascular conditions including increased cardiovascular mortality. It is therefore essential to know the major cardiovascular effects of sleep-disordered breathing during a clinical evaluation. OBJECTIVE: To analyze the cardiovascular characteristics of patients with OSA. METHODS: Patients underwent baseline polysomnography and were consecutively selected from the database of the Sleep Institute between March 2007 and March 2009. All patients were instructed to attend the clinic for blood collection, physical examination, 12-lead electrocardiogram, spirometry, cardiopulmonary exercise testing on a treadmill and transthoracic echocardiography. The study was approved by the Research Ethics Committee and recorded at http://clinicaltrials.gov/ under number: NCT00768625. RESULTS: We analyzed 261 patients and 108 controls. The main characteristics of patients with OSA were: obesity, hypertension, low plasma levels of high density lipoprotein (HDL) and increased left atrial diameter compared with controls (3.75 ± 0.42; 3.61 ± 0.41, p = 0.001), respectively. These associated characteristics correspond to a 16.6 increase in the likelihood of OSA regardless of reporting any symptoms of this disorder, such as sleepiness or snoring. CONCLUSION: In the sample studied, the mostly found cardiovascular profile of patients with OSA was: obesity, hypertension, low plasma levels of HDL and left atrial diameter increased.

Papel do sistema nervoso autônomonas arritmias cardíacas / Role of the autonomic nervous system in cardiac arrhythmias

As arritmias cardíacas apresentam comportamento eletrofisiológico, manifestação clínica, prognóstico e resposta terapêutica diferentes na população. Sendo assim, a compreensão dos mecanismos envolvidos na gênese da anormalidade do ritmo cardíaco é fundamental para nortear a terapêutica. O sistema nervoso autônomo participa ativamente da eletrofisiologia da célula cardíaca e dos mecanismos relacionados ao desencadeamento das arritmias cardíacas. Dentre as arritmias supraventriculares, a fibrilação atrial merece destaque. Estudos avaliando a variabilidade da frequência cardíaca demonstram importante modificação autonômica antecedendo um quadro defibrilação atrial. Tanto a ativação simpática quanto a estimulação parassimpática podem participar da manutenção dessa arritmia. Além disso, métodos que reduzem a inervação autonômica também reduzem a incidência de arritmias atriais, sugerindo que a neuromodulação possa ser uma ferramenta promissora no controle dessa arritmia. As arritmias ventriculares também se relacionam ao comportamento autonômico. O infarto agudo do miocárdio ocasiona denervação das fibras simpáticas na cicatriz e as áreas de intensa fibrose perdem a capacidade de responderem a estimulação simpática; entretanto asregiões próximas a cicatriz apresentam um encurtamento do período refratário para a estimulação simpática de forma heterogênica predispondo a ocorrência da ectopias ventriculares. Dessa forma, a investigação do sistema nervoso autônomo no desencadeamento e manutenção das arritmias cardíacas é uma linha de pesquisa promissora e a maior compreensão dos mecanismos autonômicos irá propiciar novas ferramentas de controle das anormalidades do ritmo cardíaco...

Cardiac arrhythmias present varying electrophysiological behavior, clinical manifestation, prognosis, and therapeutic response in the population. An understanding of the mechanisms involved in the genesis of heart rhythm disorders is there fore essential for guiding the therapy. The autonomic nervous system plays an active role in the electrophysiology of the cardiac cells and the mechanisms that trigger cardiac arrhythmias. Atrial fibrillation, one of the supraventricular arrhythmias, deserves special attention. Studies to evaluate heart rate variability have demonstrated important modifications preceding an episode of atrial fibrillation. Both sympathetic activation and parasympathetic stimulation can play a role in the persistence of this arrhythmia. More over, methods that reduce autonomic innervation also reduce the incidence of atrial arrhythmias, suggesting that neuromodulation can be a promising tool in the control of this arrhythmia. Ventricular arrhythmias are also related to autonomic behavior. Acute myocardial infarction leads to denervation of the sympathetic fibers in the scar tissue, and the areas of intense fibrosis lose their capacity to respond to sympathetic stimulation, while the regions close to thescar tissue present heterogeneous refractory period shortening for sympathetic stimulation, predisposing to the occurrence of ventricular ectopic beats. Thus, the investigation of the autonomic nervous system in the triggering and persistence of heart arrhythmias is a promising line of research, and a better understanding of the autonomic mechanisms involved will provide new tools for the control of heart rhythm disorders...